Tagged Questions

A stream cipher is an encryption algorithm which encrypts arbitrary length plain text, using a (fixed length) key. Some stream ciphers generate a key stream from only the key, which is then XOR-combined with the plain text, others feed back plain text or cryptotext into the algorithm to create the ...

I'm doing a lot of research since I'm doing an internship for a company where I need to upgrade their security level. Their own protocol needs a cryptographic upgrade and I'm leaning towards AES since ...

I'm particulary interested on knowing if the output of the AES-128-CTR ciphertext is always going to have the same size as the input plaintext, or it could be padded somehow. It seems so from my tests ...

I was being argued that stream cipher's key that is the length of the message must be sent to the destination for them to be able to decrypt the message.
My point is don't you only have to send the ...

The AEAD construction for chacha20-poly1305 described in the IETF proposal [1] encodes message lengths into the text that is to be hashed. The newer proposal [2] goes further and pads associated data ...

If a wise person was unsure about which commercial cryptography standards are truly secure from the fascist powers that be, it would seem the obvious option for companies and individuals is to now use ...

I am currently implementing Salsa20 from the specification as an exercise in learning and self-flagellation.
I have Sections 1-7 passing the test examples provided. I am now stuck on Section 8, The ...

To obfuscate data I made up this method on the spot without planning since the goal wasn't real encryption.
At first I though this cannot be real encryption but after revisiting the code and reading ...

I learnt that a Combined Linear Congruential Generator (cLCG) has better properties than a Linear Congruential Generator (LCG). For those who don't know what a cLCG is, here are three links that might ...

I am making an encryptor software for a stream cipher with my own PRNG as a project for an inter school science competition. How can I make one so that after it generates the pseudo random nos. it can ...

I am trying to make a pseudo-random number generator so that I can use it in a synchronous stream cipher for encrypting plain text. I want it to generate numbers which are as random as possible.
What ...

Recently, a new cipher called Spritz has been released by Ronald L. Rivest and Jacob Schuldt. It should be a "drop-in replacement" for RC4.
There are many differences to RC4, Spritz is "spongy" and ...

I am learning about LFSR sequence and I came across this question:
A 16-bit message consists of two ASCII characters. This message was encrypted
with a one-time pad, and the key for the one-time pad ...

I've been taking a crypto course online. I have a good idea how PRG's and Stream Ciphers work, but I'd love to get some input to help visualize what is actually happening. I understand a seed is used, ...

We are implementing searchable encryption techniques proposed by Song et al in Java for a paper[1]. The schemes need a Stream Cipher for achieving search over encrypted data.
The stream of random bits ...

Cipher modes typically assume data is streamed or read from a reliable channel with guaranteed ordering. However, many communication transports, such as UDP, are not reliable and don't guarantee order ...

Is it possible to create a streaming mode of operation where the reuse of a nonce does not destroy confidentiality?
In this question it would be allowed for the streaming mode to leak if ciphertexts ...

The simplest way to generate truly random numbers for OTP keys is to measure the time in milliseconds between each keystroke on a keyboard. The randomness depends on the user typing in various speeds. ...

While thinking about this recent question about a hash-then encrypt design, I reread the MAC-encrypt vs. encrypt-MAC question and noticed this answer quoting a paper showing that MAC-then-encrypt is ...

Most descriptions that explain how streamciphers work (like the one on Wikipedia), tend to describe a model that boils down to a simple “$ciphertext = plaintext \oplus stream$”, where the stream is ...

As far as I understand:
The primary disadvantage associated with stream ciphers is the need for a random and unique key for each run in order to protect against reused-key attacks.
OFB/CFB/CTR block ...

I'm doing a piece of coursework for Uni and the task is to break a Vernam Cipher. So we have a randomly generated key which is as long as the message. It gets used for all the messages sent from that ...

Can anyone comment if the stream cipher described here is safe? The author claims it to be unbreakable, but does not provide any evidence or proof to support this. For completeness, I have reproduced ...